Research on a planning method for switching moments in hybrid manufacturing processes

Abstract

A hybrid process that combines metal additive manufacturing and milling could overcome the deficiencies of a single metal additive manufacturing process, such as poor stability, low precision, and bad surface roughness. Many researchers have performed a great deal of work related to the hybrid process. Nevertheless, few of these researchers have studied the specific switching moments between the additive and subtractive processes. To decrease the frequency of switching the parts between stations in a hybrid process, this paper presents a process planning method that is based on two types of moments for appropriate switching between welding and milling — Switching Moments to Avoid Interference (SMAI) and Switching Moments to Eliminate Cumulatinive Error (SMECE) in the vertical direction. A hybrid machining system based on arc welding and milling (HAWM) is designed. Experiments for fabricating workpieces with internal and external surfaces are performed to demonstrate the feasibility of SMAI. By performing a comparison with the existing method of milling every single layer or every few layers, we determined that the proposed method requires fewer times of switching the parts between stations and the efficiency improves in the switching process. Additionally, an experiment of a tapered-surface workpiece is carried out to indicate the efficacy of SMECE.